I found a grey bug with black spots crawling in my bathroom what is it
Will County Illinois
Unfortunately, there is no way to identify "grey bug with black spots" without pictures. Can you please attach photos. See this Clemson Home and Garden Information Center (HGIC) fact sheet on taking good photos for your Extension Agent (https://hgic.clemson.edu/how-to-take-good-photos-for-your-extension-agent/) for photo pointers that will help both you and me.
I encourage you to contact your Will County University of Illinois Extension office at https://extension.illinois.edu/gkw especially if specimens are particularly small as the agent can put the specimens under a scope or direct you to diagnostic lab services through the University of Illinois Extension.